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Re: dataset syntax metadata

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 26 Sep 2012 15:09:46 +0100
Message-ID: <50630CAA.20004@epimorphics.com>
To: public-rdf-wg@w3.org


On 26/09/12 13:53, Sandro Hawke wrote:
> I'm surprised at some of the responses about the metadata questions in
> my "Dataset Syntax - checking for consensus" email [1].
>
> When people publish RDF for real, don't they usually put some triples in
> it which indicates who created it, when it was created, and maybe why?
> Maybe some folks don't do this, but many people consider this an
> essential practice.   My sense is that every computer format either has
> a metadata mechanism built into it, or one somehow gets hacked in later
> (like the javadoc conventions).  In a few cases (like the Adobe formats)
> that metadata is expressed in RDF.

We have RDF -  it can already express metadata!

> When people publish an RDF dataset, aren't they going to want to do the
> same thing?

Dunno - maybe they are just putting a collection of graphs on the web 
and linking to it (e.g. N-Quads dumps).

The "what it is" and "where it came from" is out-of-band e.g. on the web 
page linking to the file.

> Yes, sometimes you can just throw that metadata into a named graph, but
> what if (a) you don't get a chance to tell the consumer which named
> graph you put it in, and (b) some named graphs are opaque/untrustred,
> perhaps because they contain old information or information from other
> souces (eg a Web Crawl).    (While these might not be the cases you work
> with, it seems to me they'll be quite common if this syntax ever catches
> on.)
>
> Folks who are not convinced we need a metadata mechanism -- how do you
> imagine solving this problem?  How can someone reading a serialized
> dataset figure out which triples are the metadata?

Can't they look for it with a query?

SELECT * { GRAPH ?g { :s rdf:type :metadataRecord } }

although the unnamed graph is a good place to put it IMO.

Just don't invent a fixed name for the metagraph.

	Andy
Received on Wednesday, 26 September 2012 14:10:24 GMT

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